This invention relates to a long-acting preparation of cefalexin. Cefalexin [7-D-2-amino-2-phenylacetamido)-3-methyl-3-cephem-4-carboxylic acid monohydrate] has been used widely. It is one of the few oral cephalosporins to be marketed. It is effective against many infections, and is rapidly and for the most part absorbed through the digestive organ. A major portion is excreted in urine without being subjected to any biotransformation in the body.
However, the rapid decrease in its blood level after 1 to 2 hours from administration requires a patient to take the drug usually more than four times a day for an efficient therapy.
This problem is solved by the present invention by making a long-acting preparation of cefalexin comprising normal cefalexin and a coated cefalexin which is effective, safe and convenient for a patient, enabling twice daily administration of the drug, i.e., at 12 hour intervals, which effectively avoids possible interruption of patient's sleep.
In other words, it has now been found that one of the methods for maintaining the necessary blood level of cefalexin in man for a required period comprises the administration of normal and slowly releasing cefalexin preparations practically at the same time.